#![deny(
    unsafe_code,
    missing_docs,
    missing_debug_implementations,
    missing_copy_implementations,
    elided_lifetimes_in_paths,
    rust_2018_idioms,
    clippy::fallible_impl_from,
    clippy::missing_const_for_fn
)]
#![doc(html_logo_url = "https://avatars0.githubusercontent.com/u/55122894")]
//! ## Dart Bindgen

//! Generate Dart FFI bindings to C Header file.

//!

//! ### Supported C Language Features

//! - Functions

//! - Function Pointer (aka `callback`)

//! - Simple structs (NOTE: Nested structs is not supported yet, open a PR?)

//!

//! ## Example

//! in your `build.rs`:

//! ```rust,ignore

//!  let config = DynamicLibraryConfig {

//!       ios: DynamicLibraryCreationMode::Executable.into(),

//!       android: DynamicLibraryCreationMode::open("libsimple.so").into(),

//!       ..Default::default()

//!   };

//!   // load the c header file, with config and lib name

//!   let codegen = Codegen::builder()

//!       .with_src_header("simple-ffi/include/simple.h")

//!       .with_lib_name("libsimple")

//!       .with_config(config)

//!       .build()?;

//!   // generate the dart code and get the bindings back

//!   let bindings = codegen.generate()?;

//!   // write the bindings to your dart package

//!   // and start using it to write your own high level abstraction.

//!   bindings.write_to_file("simple/lib/ffi.dart")?;

//! ```

use std::{
    collections::HashMap,
    fmt, fs,
    io::{self, Write},
    path::PathBuf,
};

use clang::{Clang, Entity, EntityKind, Index, Type, TypeKind};
use log::debug;

use config::DynamicLibraryConfig;
use dart_source_writer::{DartSourceWriter, ImportedUri};
use enumeration::{Enum, EnumField};
use errors::CodegenError;
use func::{Func, Param};
use structure::{Field, Struct};

/// Bindgens config for loading `DynamicLibrary` on each Platform.

pub mod config;
mod dart_source_writer;
mod enumeration;
mod errors;
mod func;
mod structure;

/// Abstract over Func, Struct and Global.

trait Element {
    /// Get the name of this element

    fn name(&self) -> &str;

    /// Optional documentation of this element

    fn documentation(&self) -> Option<&str>;

    /// Used to Write the Current Element to the Final Source File

    fn generate_source(&self, w: &mut DartSourceWriter) -> io::Result<()>;
}

/// Dart Code Generator

pub struct Codegen {
    src_header: PathBuf,
    lib_name: String,
    allo_isolate: bool,
    config: DynamicLibraryConfig,
    elements: HashMap<String, Box<dyn Element>>,
}

impl Codegen {
    /// Create new [`Codegen`] using it's Builder

    pub fn builder() -> CodegenBuilder { CodegenBuilder::default() }

    /// Generate the [`Bindings`]

    pub fn generate(mut self) -> Result<Bindings, CodegenError> {
        debug!("Starting Codegen!");
        debug!("Building dsw");
        let mut dsw = Self::build_dsw();
        debug!("dsw is ready");
        self.generate_open_dl(&mut dsw)?;
        let clang = Clang::new()?;
        let index = Index::new(&clang, true, false);
        debug!("start parsing the C header file at {:?}.", self.src_header);
        let parser = index.parser(self.src_header);
        let tu = parser.parse()?;
        debug!("Done Parsed the header file");
        let entity = tu.get_entity();
        let entities = entity
            .get_children()
            .into_iter()
            .filter(|e| !e.is_in_system_header())
            .peekable();

        for e in entities {
            let kind = e.get_kind();
            debug!("Entity: {:?}", e);

            match kind {
                EntityKind::FunctionDecl => {
                    debug!("Got Function: {:?}", e);
                    // handle functions

                    let func = Self::parse_function(e)?;
                    self.elements
                        .insert(func.name().to_owned(), Box::new(func));
                },
                EntityKind::StructDecl => {
                    debug!("Got Struct: {:?}", e);

                    match Self::parse_struct(e, None) {
                        // if its unnamed in this case and not anonymous, then

                        // its ok, as it will be discovered by the typedef

                        // parser

                        Err(CodegenError::UnnamedStruct) => Ok(()),
                        Err(err) => Err(err),
                        Ok(s) => {
                            self.elements
                                .insert(s.name().to_owned(), Box::new(s));

                            Ok(())
                        },
                    }?;
                },
                EntityKind::EnumDecl => {
                    debug!("Got Enum: {:?}", e);

                    match Self::parse_enum(e, None) {
                        // if its unnamed in this case and not anonymous, then

                        // its ok, as it will be discovered by the typedef

                        // parser

                        Err(CodegenError::UnnamedEnum) => Ok(()),
                        Err(err) => Err(err),
                        Ok(s) => {
                            self.elements
                                .insert(s.name().to_owned(), Box::new(s));

                            Ok(())
                        },
                    }?;
                },
                EntityKind::TypedefDecl => {
                    debug!("Got Typedef: {:?}", e);

                    for child in e.get_children() {
                        match child.get_kind() {
                            EntityKind::StructDecl => {
                                debug!("Got struct in Typedef: {:?}", child);
                                let s =
                                    Self::parse_struct(child, e.get_name())?;

                                self.elements
                                    .insert(s.name().to_owned(), Box::new(s));
                            },
                            EntityKind::EnumDecl => {
                                debug!("Got enum in Typedef: {:?}", child);
                                let s = Self::parse_enum(child, e.get_name())?;

                                self.elements
                                    .insert(s.name().to_owned(), Box::new(s));
                            },
                            _ => {},
                        }
                    }
                },
                _ => {},
            }
        }
        if self.allo_isolate {
            let func = Func::new(
                "store_dart_post_cobject".to_string(),
                Some(String::from("Binding to `allo-isolate` crate")),
                vec![Param::new(
                    Some("ptr".to_string()),
                    String::from("Pointer<NativeFunction<Int8 Function(Int64, Pointer<Dart_CObject>)>>"),
                )],
                String::from("void"),
            );
            // insert new element

            self.elements.insert(
                String::from("store_dart_post_cobject"),
                Box::new(func),
            );
        }
        debug!("Generating Dart Source...");
        // trying to sort the elements to avoid useless changes in git for

        // example since HashMap is not `Ord`

        let mut elements: Vec<_> = self.elements.values().collect();
        elements.sort_by_key(|k| k.name());

        for el in elements {
            el.generate_source(&mut dsw)?;
        }
        debug!("Done.");
        Ok(Bindings::new(dsw))
    }

    fn generate_open_dl(
        &self,
        dsw: &mut DartSourceWriter,
    ) -> Result<(), CodegenError> {
        dsw.set_lib_name(&self.lib_name);
        debug!("Generating Code for opening DynamicLibrary");
        writeln!(dsw, "final DynamicLibrary _dl = _open();")?;
        writeln!(dsw, "/// Reference to the Dynamic Library, it should be only used for low-level access")?;
        writeln!(dsw, "final DynamicLibrary dl = _dl;")?;
        writeln!(dsw, "DynamicLibrary _open() {{")?;
        if let Some(ref config) = self.config.windows {
            debug!("Generating _open Code for Windows");
            writeln!(dsw, "  if (Platform.isWindows) return {};", config)?;
        }
        if let Some(ref config) = self.config.linux {
            debug!("Generating _open Code for Linux");
            writeln!(dsw, "  if (Platform.isLinux) return {};", config)?;
        }
        if let Some(ref config) = self.config.android {
            debug!("Generating _open Code for Android");
            writeln!(dsw, "  if (Platform.isAndroid) return {};", config)?;
        }
        if let Some(ref config) = self.config.ios {
            debug!("Generating _open Code for iOS");
            writeln!(dsw, "  if (Platform.isIOS) return {};", config)?;
        }
        if let Some(ref config) = self.config.macos {
            debug!("Generating _open Code for macOS");
            writeln!(dsw, "  if (Platform.isMacOS) return {};", config)?;
        }
        if let Some(ref config) = self.config.fuchsia {
            debug!("Generating _open Code for Fuchsia");
            writeln!(dsw, "  if (Platform.isFuchsia) return {};", config)?;
        }
        writeln!(
            dsw,
            "  throw UnsupportedError('This platform is not supported.');"
        )?;
        writeln!(dsw, "}}")?;
        debug!("Generating Code for opening DynamicLibrary done.");
        Ok(())
    }

    fn parse_function(
        entity: Entity<'_>,
    ) -> Result<impl Element, CodegenError> {
        let name = entity.get_name().ok_or(CodegenError::UnnamedFunction)?;
        debug!("Function: {}", name);
        let params = match entity.get_arguments() {
            Some(entities) => Self::parse_fn_params(entities)?,
            None => Vec::new(),
        };
        debug!("Function Params: {:?}", params);
        let docs = entity.get_parsed_comment().map(|c| c.as_html());
        debug!("Function Docs: {:?}", docs);
        let return_ty = entity
            .get_result_type()
            .ok_or(CodegenError::UnknownFunctionReturnType)?
            .get_canonical_type()
            .get_display_name();
        debug!("Function Return Type: {}", return_ty);
        Ok(Func::new(name, docs, params, return_ty))
    }

    fn parse_fn_params(
        entities: Vec<Entity<'_>>,
    ) -> Result<Vec<Param>, CodegenError> {
        let mut params = Vec::with_capacity(entities.capacity());
        for e in entities {
            debug!("Param: {:?}", e);
            let name = e.get_name();
            debug!("Param Name: {:?}", name);
            let ty = e
                .get_type()
                .ok_or(CodegenError::UnknownParamType)?
                .get_canonical_type();
            debug!("Param Type: {:?}", ty);
            let ty = Self::parse_ty(ty)?;
            debug!("Param Type Display Name: {}", ty);
            params.push(Param::new(name, ty));
        }
        Ok(params)
    }

    fn parse_fn_proto(ty: Type<'_>) -> Result<String, CodegenError> {
        let mut dsw = DartSourceWriter::new();
        debug!("Function Proto: {:?}", ty);
        let return_ty = ty
            .get_canonical_type()
            .get_result_type()
            .ok_or(CodegenError::UnknownFunctionReturnType)?
            .get_canonical_type()
            .get_display_name();
        let params = match ty.get_argument_types() {
            Some(arg_ty) => arg_ty
                .iter()
                .map(|ty| ty.get_display_name())
                .map(|ty| dsw.get_ctype(&ty))
                .collect(),
            None => Vec::new(),
        };
        write!(
            dsw,
            "Pointer<NativeFunction<{} Function({})>>",
            dsw.get_ctype(&return_ty),
            params.join(", ")
        )?;
        Ok(dsw.to_string())
    }

    fn parse_struct(
        entity: Entity<'_>,
        name: Option<String>,
    ) -> Result<impl Element, CodegenError> {
        if entity.is_anonymous() {
            return Err(CodegenError::AnonymousEntity);
        }

        let name = name
            .or_else(|| entity.get_name())
            .ok_or(CodegenError::UnnamedStruct)?;

        debug!("Struct: {}", name);
        let children = entity.get_children();
        let mut fields = Vec::with_capacity(children.capacity());

        for child in children {
            let name =
                child.get_name().ok_or(CodegenError::UnnamedStructField)?;

            let ty = child
                .get_type()
                .ok_or(CodegenError::UnknownParamType)?
                .get_canonical_type();
            let ty = Self::parse_ty(ty)?;
            fields.push(Field::new(name, ty));
        }
        let docs = entity.get_parsed_comment().map(|c| c.as_html());
        Ok(Struct::new(name, docs, fields))
    }

    fn parse_enum(
        entity: Entity<'_>,
        name: Option<String>,
    ) -> Result<impl Element, CodegenError> {
        if entity.is_anonymous() {
            return Err(CodegenError::AnonymousEntity);
        }

        let name = name
            .or_else(|| entity.get_name())
            .ok_or(CodegenError::UnnamedEnum)?;

        debug!("Enum: {}", name);
        let children = entity.get_children();
        let mut fields = Vec::with_capacity(children.capacity());

        for child in children {
            debug!("Enum field: {:?}", child);
            let name =
                child.get_name().ok_or(CodegenError::UnnamedEnumField)?;

            let value = child
                .get_enum_constant_value()
                .ok_or(CodegenError::UnknownEnumFieldConstantValue)?
                .1;

            fields.push(EnumField::new(name, value));
        }
        let docs = entity.get_parsed_comment().map(|c| c.as_html());
        Ok(Enum::new(name, docs, fields))
    }

    fn parse_ty(ty: Type<'_>) -> Result<String, CodegenError> {
        use TypeKind::*;
        if ty.get_kind() == Pointer {
            let pointee_type = ty
                .get_pointee_type()
                .ok_or(CodegenError::UnknownPointeeType)?;
            let kind = pointee_type.get_kind();
            if kind == FunctionPrototype || kind == FunctionNoPrototype {
                Self::parse_fn_proto(pointee_type)
            } else {
                Ok(ty.get_display_name())
            }
        } else {
            Ok(ty.get_display_name())
        }
    }

    fn build_dsw() -> DartSourceWriter {
        let mut dsw = DartSourceWriter::new();
        // disable some lints

        writeln!(dsw, "// ignore_for_file: unused_import, camel_case_types, non_constant_identifier_names").unwrap();
        dsw.import(ImportedUri::new(String::from("dart:ffi")));
        dsw.import(ImportedUri::new(String::from("dart:io")));
        let mut ffi = ImportedUri::new(String::from("package:ffi/ffi.dart"));
        ffi.with_prefix(String::from("ffi"));
        dsw.import(ffi);
        dsw
    }
}

impl fmt::Debug for Codegen {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        f.debug_struct("Codegen")
            .field("src_header", &self.src_header)
            .field("lib_name", &self.lib_name)
            .field("config", &self.config)
            .finish()
    }
}

/// The [`Codegen`] Builder

///

/// start by calling [`Codegen::builder()`]

#[derive(Clone, Debug, Default)]
pub struct CodegenBuilder {
    src_header: PathBuf,
    lib_name: String,
    allo_isolate: bool,
    config: Option<DynamicLibraryConfig>,
}

impl CodegenBuilder {
    /// The Input `C` header file

    pub fn with_src_header(mut self, path: impl Into<PathBuf>) -> Self {
        self.src_header = path.into();
        self
    }

    /// The output lib name, for example `libfoo`

    ///

    /// used for docs

    pub fn with_lib_name(mut self, name: impl Into<String>) -> Self {
        self.lib_name = name.into();
        self
    }

    /// Defines, how the dynamic library should be loaded on each of dart's

    /// known platforms.

    #[allow(clippy::missing_const_for_fn)]
    pub fn with_config(mut self, config: DynamicLibraryConfig) -> Self {
        self.config = Some(config);
        self
    }

    /// Integration with [`allo-isolate`](https://crates.io/crates/allo-isolate)

    ///

    /// This allow dart-bindgen to add the code required by allo-isolate

    /// i.e `store_dart_post_cobject` fn

    pub const fn with_allo_isolate(mut self) -> Self {
        self.allo_isolate = true;
        self
    }

    /// Consumes the builder and validate everyting, then create the [`Codegen`]

    pub fn build(self) -> Result<Codegen, CodegenError> {
        if self.lib_name.is_empty() {
            return Err(CodegenError::Builder(
                "Please Provide the C lib name.",
            ));
        }

        let config = self.config.ok_or(
            CodegenError::Builder("Missing `DynamicLibraryConfig` did you forget to call `with_config` builder method?.")
        )?;

        Ok(Codegen {
            src_header: self.src_header,
            lib_name: self.lib_name,
            allo_isolate: self.allo_isolate,
            config,
            elements: HashMap::new(),
        })
    }
}

/// A bindings using `dart:ffi` that could be written.

#[derive(Debug)]
pub struct Bindings {
    dsw: DartSourceWriter,
}

impl Bindings {
    pub(crate) const fn new(dsw: DartSourceWriter) -> Self { Self { dsw } }

    /// Write dart ffi bindings to a file

    pub fn write_to_file(
        &self,
        path: impl Into<PathBuf>,
    ) -> Result<(), CodegenError> {
        let mut out = fs::OpenOptions::new()
            .read(false)
            .write(true)
            .truncate(true)
            .create(true)
            .open(path.into())?;
        debug!("Writing Dart Source File...");
        write!(out, "{}", self.dsw)?;
        Ok(())
    }

    /// Write dart ffi bindings to anything that can we write into :D

    ///

    /// see also:

    ///  * [`Bindings::write_to_file`]

    pub fn write(&self, w: &mut impl Write) -> Result<(), CodegenError> {
        debug!("Writing Dart Source File...");
        write!(w, "{}", self.dsw)?;
        Ok(())
    }
}